P-class asteroid

astronomy

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 2, 2026

Quick Summary

P-class asteroids are a taxonomic classification of asteroids characterized by their low albedo (reflectivity) and a featureless spectral reflectance that slopes upward into the red. They have a mean albedo of 0.04.1

Currently, there are no known meteorite or naturally occurring mineralogical counterparts for P-class asteroids. However, it is theorized that their surface material may contain a significant fraction of carbon polymers or organic-rich silicates, or both.1

While P-class asteroids are not the most common type in the asteroid belt, they constitute about 4 percent of the larger asteroids (those with diameters greater than 25 km). They are found in the outer regions of the asteroid belt, dominating populations at distances of about 5 AU from the Sun.12

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

2 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

asteroid
Composition
P- and T-class asteroids have low albedos and no known meteorite or naturally occurring mineralogical counterparts, but they may contain a large fraction of carbon polymers or organic-rich silicates or both in their surface material. R-class asteroids are very rare. Their surface material has been…
Read More
P- and T-class asteroids have low albedos and no known meteorite or naturally occurring mineralogical counterparts, but they may contain a large fraction of carbon polymers or organic-rich silicates or both in their surface material. R-class asteroids are very rare. Their surface material has been…
Read More